The proposed research is designed to investigate the neural substrates of source monitoring, which involve judgments about the source of retrieved memories. Source judgments are based on memory characteristics such as perceptual information, temporal context and cognitive operations. It is hypothesized that the dorsolateral prefrontal cortex is critical to this source judgment process and that there will be hemispheric differences in activation of this region based on the memory characteristics on which a particular judgment rely. Converging evidence from two methodologies will be used to elucidate hemispheric and regional contributions to the source monitoring process. Split-brain testing and functional magnetic resonance imaging will be used in a series of experiments that manipulate specific characteristics of memories to test the experimental hypotheses.